The present invention relates to an image processing system, a projector, a portable device, and an image processing method that are capable of correcting keystone distortion.
Various different methods have been proposed for correcting keystone distortion that is generated in images projected by a projector.
One method detects the inclination of the projector and automatically corrects keystone distortion in the vertical direction, by way of example.
However, this method does not enable the user to correct keystone distortion in the horizontal direction.
For that reason, one method of correcting keystone distortion in the horizontal direction involves the user correcting the keystone distortion manually by pressing a correction switch on a remote controller while viewing the image.
However, the manual correction of the keystone distortion is troublesome to the user, making it difficult to perform suitable correction manually.
In the light of the above problem, methods have been proposed for correcting image distortion automatically, such as that disclosed in Japanese Patent Application No. 2001-036086 (Japanese Patent Publication No. 2002-112148).
However, this method only discloses a method of correcting keystone distortion by detecting the distance up to the installation plane of the projector and the inclinations in the horizontal and vertical directions with respect to the horizontal plane of the projector.
For that reason, that method is based on the premise that the projection screen is positioned facing the projector, as stated in that application.
If the projector is positioned in a direction at an angle to the projection screen, however, keystone distortion is generated in the horizontal direction (sideways direction).
It is therefore difficult to use that published method to correct keystone distortion in the horizontal direction both automatically and appropriately.